Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> writes:
> But I think there is another issue in sequential scan cost. We have
> zero startup cost for sequential scan. But why?
Because it's what the mental model of startup cost says it should be.
Also, I do not think we can change that without a whole lot of unpleasant
side effects on cases that work well today. Have you even checked to
see how much of the regression tests break with this change?
regards, tom lane